Physical and Physiological Factors Associated with Success in Professional Alpine Skiing

G. Neumayr 1 H. Hoertnagl 1 R. Pfister 1 A. Koller 1 G. Eibl 2 E. Raas 1 Physical and Physiological Factors Associated with Success in Professional Alpine Skiing Abstract Scientific data on the physiological profile of world class skiers are sparse. During the last decade the Austria Ski Team was the most successful in the world. It was the objective of this study to describe the physical and physiological characteristics of World Cup (WC) skiers. Twenty female and 28 male members of the Austrian WC Ski Team were examined pre- and post-seasonally from 1997 to 2000. Physical parameters such as age, height, body mass, body mass index, percent body fat and thigh circumference were recorded from each athlete. The physiological variables investigated consisted in the aerobic power and in the muscle strength of the lower limbs. Racing performance was defined by the WC ranking position. The athlete's aerobic performance capacity was assessed by maximal exercise testing on a bicycle ergometer, and the isokinetic muscle strength of the knee extensor and flexor muscles by the use of a computer-interfaced dynamometer. From 1997 to 2000 about half (48 %; n = 106) of all alpine WC racing events (n = 221) were won by the athletes investigated. The typical world class skier is in the mid-twenties (25.2 y [,]; 27.6 y [<]). The mean values for height Introduction The demands of professional alpine skiing are complex and require special abilities. In contrast to other sports, nothing is documented about the typical physical and physiological profile of World Cup (WC) skiers. The information available is limited and very specific. It is restricted to former data on the motor dexterity and physical features of world class athletes 25 years ago were 1.66 m (,) vs.1.81m(<), for body mass 65.1 kg (f) vs. 87 kg (<) and for the percentage of body fat 24.5% (,) vs. 15.8 % (<). The maximum power output was 4.3 0.4 (,) and 4.7 0.4 W/kg (<), the corresponding values for VÇ O 2 max were 55 3.5 (,) and 60 4.7 ml/kg/min (<). The maximal values for peak torque and work for knee extension amounted to 206 21 (,) and 334 43 Nm (<), and 2690 364 (,) and 4414 629 J (<), respectively. In both sexes there were neither significant laterality nor dysbalance. The hamstring/quadriceps ratios were between 0.57 ± 0.60. Among all physical and physiological variables, only the aerobic power in males was found to be strongly correlated (r = 0.947; p = 0.001 for W max ; r = 0.964; p < 0.001 for VÇ O 2 max) to racing performance. The study proves the practical experience that success in professional alpine skiing is not related to single physiological variables. Two main factors, however, are crucial, i. e. high levels of aerobic power and muscle strength. Key words Alpine skiing aerobic power muscle strength anthropometrical features [7]. In a more recent methodical study the niveau of muscle strength of the lower limbs was investigated in the Swiss Ski National Team of 1993 [14]. Since 1964, when the first Olympic Winter Games were held in Innsbruck, all alpine skiers of the Austrian Ski Federation have been examined for their physical fitness at the Institute of Sports Medicine and Cardiovascular Medicine at the University Clinics 571 Affiliation 1 Institute of Sports Medicine and Cardiovascular Medicine, University Clinics of Innsbruck, Austria 2 Department of Biostatistics, University of Innsbruck, Austria Correspondence G. Neumayr MD Institute of Sports Medicine and Cardiovascular Medicine University Clinics of Innsbruck Anichstraûe 35 6020 Innsbruck Austria Phone: +39 0474 917111 Fax: +39 0474 917171 E-Mail: guenther.neumayr@sb-bruneck.it Accepted after revision: February 24, 2003 Bibliography Int J Sports Med 2003; 24: 571±575 Georg Thieme Verlag Stuttgart New York ISSN 0172-4622

of Innsbruck. For many years the Austria Ski Team has been the most successful in the world, but especially between 1997 and 2000, there was an outstanding period of international success when about half of all WC events were won by the Austrian Ski Federation. During this period all Austrian professional alpine skiers were examined two to three times a year at our Institute for their physical fitness, the anthropometrical profile and the physiological capacities. It was the objective of the present study to describe the physical and physiological variables (i. e aerobic power and muscle strength of the lower limbs) of WC skiers and to define the most important determinants essential for success in professional alpine skiing. Table 1 Anthropometrical characteristics of female elite skiers in the season 1999/2000 Mean value SD Range Age (y) 25.2 3.9 19 ±33 Height (m) 1.66 0.05 1.59 ±1.76 Body mass(kg) 65.1 6.5 52.5 ±77 BMI (kg/m 2 ) 23.6 1.7 19.6 ±26.1 Percent body fat (%) 24.5 3.6 16.3 ±30.6 Thigh circumference (cm) 59 2.5 53 ±63 SD = standard deviation, BMI= body mass index 572 Material and Methods Physical variables From 1997 to 2000 all 20 female and 28 male members of the Austrian WC Ski Team were examined pre- and post-seasonally. With respect to the 4 WC disciplines, i. e. down hill (dh), super giant (sg), giant slalom (gs) and slalom (sl), the athletes were seperated into specialists competing in one or two disciplines (ªtechnique groupº: sl + gs; ªspeed groupº: sg + dh) and allrounders (ªall-rounder groupº: gs + sg + dh) participating in three. Physical parameters such as age, height, body mass, body mass index, percent body fat and thigh circumference were recorded from each athlete. The athlete's aerobic performance capacity was assessed by symptom-limited maximal exercise testing (increment 50 W/ 3 min) on a bicycle ergometer (ER 800, Ergoline, Bitz, Germany). Minute BTPS ventilation (VE), STPD oxygen uptake (VÇ O 2 ) and STPD carbon dioxide production (VÇ CO 2 ) were measured by an open circuit spirometry (Oxycon pro, Jaeger, Würzburg, Germany; CPX Medical Graphics). Capillary blood samples were taken from the ear lobe immediately after each workload to determine lactate concentration (lactate analyzer Ebio plus, Eppendorf, Hamburg, Germany). The lactate value attained during the last workload was considered to be maximal (Lac max ). Measurements of muscle strength The isokinetic strength of the knee extensor and flexor muscles (concentric muscle action) was assessed by the use of a computer-interfaced dynamometer (Cybex 6000, Ronkomkoma, NY, USA). Standardized loading of the thigh muscles was done for both sides at angular velocities of 608/s (3 repetitions) and 2408/s (30 repetitions). Twenty seconds of rest were held between the 3 repetitions at 608/s and the 30 repetitions at 2408/s. Recording of racing performance The headquarters of the Austrian Ski Federation was asked to provide all WC racing results of the athletes investigated for the seasons 1997/1998 to 1999/2000. For the statistical analyses we considered the number of top 3-WC places (i. e. 1st ± 3rd) as well as the WC ranking position in the respective discipline. We controlled the whole information by checking the official result lists provided on-line by the Federation International de Ski (FIS). Table 2 Statistical analyses All analyses were performed by using the SPSS software package (version 9.0; Chicago, IL, USA). Results are expressed as mean values standard deviation (SD). The athlete's racing performance (i. e. WC ranking position; number of top 3-WC places) and the pre-seasonal, physical and physiological parameters were evaluated for trends for each year and group by repeated measures analysis of variance (ANOVA). Correlations between them were calculated by simple linear regression analyses and were described by the correlation coefficient r. For the comparison of variables for specialists (technique group; speed group) and allrounders the Mann-Whitney test and the Kruskal-Wallis test were used. The changes over the seasons were calculated by the Wilcoxon test and the Friedman test. Statistical significance was assumed at a level of p < 0.05. Results Anthropometrical characteristics of male elite skiers in the season 1999/2000 Mean value SD Range Age (y) 27.6 3.5 21 ±34 Height (m) 1.81 0.06 1.72±1.96 Body mass (kg) 87.0 7.1 72 ±103 BMI (kg/m 2 ) 26.5 1.7 22.2 ±29.1 Percent body fat (%) 15.8 3.7 9.4 ±21.3 Thigh circumference (cm) 64.5 1.5 59 ±67 SD = standard deviation, BMI= body mass index Physical variables The mean values for age, height, body mass, percent body fat and thigh circumference recorded pre-seasonally in 1999/2000 are given in Table 1 for females and in Table 2 for males. The physical variables did not significantly differ over the seasons. There were, of course, significant anthropometrical differences between the sexes, but none between specialists and allrounders. Neumayr G et al. Physical Profile of Elite Skiers¼ Int J Sports Med 2003; 24: 571 ± 575

Table 3 Various performance parameters of elite skiers in a maximal exercise test (mean values) Table 4 Mean values of peak torque and work for knee extension (ext) and flexion (flex) in elite skiers (right leg) season 1997/1998 1998/1999 1999/2000 gender, <, <, < season 1997/1998 1998/1999 1999/2000 gender, <, <, < W 2mmol 1.8 2.3 1.7 2.4 2.0 2.6 (SD) 0.3 0.3 0.3 0.3 0.3 0.3 W 4mmol 2.6 3.2 2.9 3.4 3.0 3.6 (SD) 0.4 0.2 0.3 0.3 0.2 0.3 W max 3.7 4.2 4.3 4.4 4.3 4.7 (SD) 0.5 0.3 0.3 0.4 0.4 0.4 VO 2 max 55.8 57.5 56.9 59.5 55.6 58.7 (SD) 3.5 3.0 3.9 4.7 4.9 3.2 Lac max 10.6 11.3 11.4 11.5 12.0 12.0 (SD) 1.3 1.2 1.9 2.3 0.9 1.6 RQ 1.11 1.12 1.13 1.12 1.12 1.13 (SD) 0.01 0.02 0.02 0.02 0.02 0.02 AT 78 78 74 76 75 78 (SD) 7 5 5 4 6 5 SD = standard deviation; W = power output [W/kg] at various lactate concentrations; W max = maximum power output [W/kg]; VÇO 2 max = maximal oxygen uptake [ml/kg/min]; Lac max = maximal lactate concentration [mmol/l]; RQ = respiratory quotient; AT = anaerobic treshold [%]. The gender differences and the development of aerobic power over the years are illustrated in Table 3. In both sexes there were significant increases in the submaximal and maximal ranges of aerobic power. In females the maximum power output (W max ) rose significantly by 16 % in just one year (W max = 3.7 [1997] 4.3 W/kg [1998], p = 0.0019) and has stagnated since then. In male athletes a more continuous increase of 12 % was achieved over two seasons (W max = 4.2 [1997] 4.7 W/kg [1999]; p < 0.001). The improvements of aerobic power in the submaximal ranges (W 2mmol,W 4mmol ) were similar to those of W max.in women W 2mmol increased by 11 % and W 4mmol by 15 % whereas in men the rise amounted to 13 % for both W 2mmol and W 4mmol. Comparing the aerobic power of specialists (technique group; speed group) with all-rounders, no significant differences in W max or VÇ O 2 max were found, even though there were trends towards better aerobic power in specialists for both sexes. In 1999/2000, for example, in females the highest values of W max were recorded in the technique group with 4.49 0.22 W/kg vs. 4.21 0.47 W/ kg in the allrounders. In males the highest values of W max amounted to 4.84 0.38 W/kg in the speed group vs. 4.63 0.34 W/kg in the technique group vs. 4.58 0.32 W/kg in the all-rounders. Correlating the parameters of aerobic power with the racing performance, positive trends could be found in both sexes for specialists but were not seen for allrounders. However, a strong correlation between the WC ranking position and W max (r = 0.947; p = 0.001) or VÇ O 2 max (r = 0.964; p < 0.001) was only found in the male speed group (sg + dh) in 1998. Muscle strength The mean values for peak torque and work for knee extension and flexion are given in Table 4 for both sexes. In both sexes there was no significant difference between the right and the left leg peak torque ext (Nm) 200 326 197 334 206 314 (SD) 32 45 24 43 21 44 work ext (J) 2438 4406 2587 4414 2690 3964 (SD) 375 618 393 629 364 1231 peak torque flex (Nm) 115 187 114 187 119 186 (SD) 19 23 16 21 15 24 work flex (J) 1763 2749 1803 2813 1904 2739 (SD) 316 376 331 463 267 458 Table 5 (i. e. laterality), and no significant development over the seasons. However, there were marked gender-specific differences. Females achieved about 60% of the male values for peak torque for both extension and flexion and about 55 ± 65 % of the male values for work. In both sexes the mean hamstring/quadriceps ratios were within 0.57 ± 0.60 during the entire period of investigation. No significant differences were seen in the niveau of muscle strength between specialists and all-rounders. A correlation between the variables of muscle strength and the racing performance was not found in either of the sexes. Racing performance Between 1997 and 2000 nearly half of all WC events (48%) were won by the athletes investigated, and about one-third of all 2 nd (35%) and 3 rd (42 %) places as well. A survey of the top 3-WC placements achieved by the Austria Ski Team is given in Table 5. Discussion Racing performance in the World Cup (WC) of the Austria Ski Team from 1997 to 2000 season 1997/1998 1998/1999 1999/2000 1997 ± 2000 gender female male female male female male female+male n8 of races 33 37 36 35 40 40 221 WC placements 1. place 2 25 20 19 14 26 106 (48 %) 2. place 6 15 11 18 8 19 77 (35 %) 3. place 6 19 9 21 15 25 95 (42 %) 1. ±3. places* 14/99 59/111 40/108 58/105 37/120 70/120 278/663 1. ±3. places (%) 14 53 34 50 31 58 42 *presented as number of achieved placements/total placements; n8 = number The assessment of the physical and physiological profile of athletes remains an area of scientific interest for the estimation and prediction of racing performance in many sports such as cycling, distance running, racewalking, cross-country skiing, triathlon and American football [1 ±6, 8 ± 11,13]. In endurance sports, such as running and bicycling, crucial determinants of 573 Neumayr G et al. Physical Profile of Elite Skiers¼ Int J Sports Med 2003; 24: 571 ±575

574 performance can be identified by sport-specific testing in the laboratory [3 ± 6, 8]. Variables, such as maximum oxygen consumption (VÇ O 2 max), oxygen consumption or velocity at various lactate thresholds etc., serve as predictors of competition performance. In more complex kinds of sports, however, the predictive value of such determinants becomes less important. Alpine skiing, for example, requires a variety of qualities. Besides material factors (ski and equipment) a variety of human skills consisting of sports-specific (ski technique) and sports-unspecific features (e. g. the athlete's physical, physiological and psychological profile) is responsible for success in competition. The sportsspecific abilities were predominantly trained by substantial ski technique training in the late summer or autumn when the first snow courses on the glacier start. In the preceding spring and summer period, however, the athlete has to train a multitude of sports-unspecific capacities, i. e. aerobic and anaerobic power, muscle strength, motor dexterity, psychological factors, concentration etc. and muscle strength can then be scrutinized in the laboratory setting pre-seasonally. It was the objective of the present study to describe the physical characteristics and the physiological performance parameters of elite skiers. The very successful Austria Ski Team served as the study population from 1997 to 2000. The results obtained appear to be homogeneous with respect to sexes and WC discipline and are discussed under the following three aspects. Anthropometrical profile The typical world class skiers are in the mid-twenties. Their mean values for height and body mass were 1.66 m (,) v s. 1.81 m (<) and 65.1 kg (,) vs. 87 kg (<), respectively. They dispose of a muscular physique providing the advantages of large leverage combined with optimal power. These features are of advantage in generating torque at high angular velocities to manage the demands arising from the modern equipment and the new carving technique. Rather heavy body masses are considered to be a competition advantage, especially in speed events (dh + sg) in the sections of low technical difficulties. The physical features of today's Austrian WC skiers are in good accordance with former anthropometrical data of Swiss WC athletes [14]. In 1993 the mean values for age and body mass were 25 y and 65 kg in female Swiss WC skiers. The respective values for males were 26 y and 79 kg, which is about 10% less in body mass compared with the Austrian athletes. This trend towards heavier body masses is likely due to an increased muscle mass of the upper part of the body and of the upper limbs caused by today's enhanced power training of the upper body. The muscle masses of the lower limbs, however, did not significantly change over the years, obvious by constant values for muscle strength and thigh circumference [14]. The differences in the anthropometrical profile become even more distinct when comparing today's world class skiers with those 25 years ago [7] or with recreational skiers [12]. No correlation was found between any anthropometrical feature and racing performance. This, however, was not surprising to us as in alpine skiing all motor features, i. e. endurance, strength, velocity, flexibility and coordination, as well as psychological factors like motivation, concentration and the ability to sustain stress, contribute to competition performance. In alpine skiing all racing events last between 45 seconds and 2.5 minutes. Hence the energy supply is provided by the aerobic and anaerobic metabolism. The anaerobic capacity meets a substantial part of the immediate energy demands during training and competition. Own investigations in the field show Lac max to range between 12 and 15 mmol/l after single competitive runs (unpublished data). Normally no special training is required to establish the anaerobic power, it is usually sufficiently trained by the ski-specific snow training alone. In contrast, a high aerobic capacity is essential for several reasons: 1) to meet the predominant energy demands of training and competition, 2) to provide a fast and sufficient recovery in the short intervals between the runs and races, and 3) to sustain the overall stress of a long racing season lasting 4 ± 5 months for being successful even in the second half when Olympic games or world championship are held. Elite skiers therefore undergo substantial endurance training to establish a level of aerobic power sufficient enough to endure the mainly static loads of ski racing as well as the overall stress of a long season. The mean maximum power output amounts to 4.3 W/kg (VÇ O 2 max = 56 ml/ kg/min) in female Austrian WC skiers, and to 4.7 W/kg (VÇ O 2 max = 60 ml/kg/min) in males. These values derive from about 6 ± 7 hours of endurance training per week during the summer period. There is a tight relationship between success and aerobic power. This observation does not only correspond to our practical experience gained over the last decades, it is also affirmed by the present study. In a regression analysis a strong positive correlation was found in men between the aerobic power and their WC ranking position. We did not find such a relationship in women. Nevertheless, it is mentionable that in females the significant improvement of aerobic power (W max = 16 % from 1997 ± 1998) was followed by a boost in victories (+ 900%) and top-three WC placements (+ 143 %) in the subsequent season 1998/99 (see Table 5). Comparing specialists (technique group; speed group) and all-rounders no significant differences in the aerobic power were found. Nevertheless, there was a trend in both sexes towards slightly enhanced values of W max and VÇ O 2 max in specialists which may be explained by the higher volume of time-consuming, technique-specific ski training of all-rounders. Muscle strength Both, the more aggressive ski material and equipment as well as the current carving technique have necessitated to generate torque at high angular velocities as one special feature of modern skiing. The isokinetic dynamometer is a device enabling the characterisation of the explosive force production and of the ability to maintain it as long as possible. The results obtained show a good level of peak torque and work in both sexes. They are again in good accordance with those of the Swiss athletes of 1993 [14] who had even higher mean values of peak torque for the knee extension (300 Nm [,]; 434 Nm [<]). In both sexes there were neither major laterality nor dysbalances, obvious by very similar values for both sides and by balanced hamstring/quadriceps ratios, respectively. Both, lacking laterality and dysbalance are proven to be effective in the prophylaxis of knee traumata, the most frequent injury in alpine skiing. The Neumayr G et al. Physical Profile of Elite Skiers¼ Int J Sports Med 2003; 24: 571 ± 575

lacking difference in muscle strength between specialists and all-rounders suggests that the musculoskeletal strains are rather similar within the 4 WC disciplines demanding equal requisites for muscle strength. The practical experience in alpine skiing considers the muscle force of the lower limbs to belong to the most decisive determinants. Nevertheless, in this analysis we did not find any respective correlation between variables of muscle strength and WC ranking. The most likely explanation for this is that beyond a certain cut-off value no further association between strength and racing performance can be seen. We consider the level of muscle strength found in our athletes that good that no statistical correlation could be found anymore. This is the first study to describe the physical and physiological variables of alpine world class skiers. It proves that in professional skiing racing performance depends on several variables and cannot be predicted from single physiological parameters. However, among these variables two appear to be crucial, i. e. aerobic power and muscle strength of the lower limbs. References 1 Bale P, Colley E, Mayhew JL, Piper FC, Ware JS. Anthropometric and somatotype variables related to strength in American football players. J Sports Med Phys Fitness 1994; 34: 383± 389 2 Baron R. Aerobic and anaerobic power characteristics of off-road cyclists. Med Sci Sports Exerc 2001; 33: 1387 ± 1393 3 Coyle EF, Feltner ME, Kautz SA, Hamilton MT, Montain SJ, Baylor AM, Abraham LD, Petrek GW. Physiological and biomechanical factors associated with elite endurance cycling performance. Med Sci Sports Exerc 1991; 23: 93 ±107 4 Farrell PA, Wilmore JH, Coyle EF, Billing JE, Costill DL. Plasma lactate accumulation and distance running performance. Med Sci Sports 1979; 11: 338± 344 5 Hagberg JM, Coyle EF. Physiological determinants of endurance performance as studied in competitive racewalkers. Med Sci Sports Exerc 1983; 15: 287 ±289 6 Helgerud J, Engen LC, Wisloff U, Hoff J. Aerobic endurance training improves soccer performance. Med Sci Sports Exerc 2001; 33: 1925± 1931 7 Kornexl EJ. Das sportmotorische Eigenschaftsniveau des Alpinen Rennläufers. Ph.D. Thesis, University of Innsbruck, Austria, 1977 8 Mahood NV, Kenefick RW, Kertzer R, Quinn TJ. Physiological determinants of cross-country ski racing performance. Med Sci Sports Exerc 2001; 33: 1379 ± 1384 9 Mujika I, Padilla S. Physiological and performance characteristics of male professional road cyclists. Sports Med 2001; 31: 479 ±487 10 O'Toole ML, Douglas PS, Hiller WD. Applied physiology of a triathlon. Sports Med 1989; 8: 201 ± 225 11 O'Toole ML, Douglas PS. Applied physiology of a triathlon. Sports Med 1995; 19: 251±267 12 Piper FC, Ward CH, McGinnis PM, Milner EK. Prediction of alpine ski performance based upon selected anthropometrical and motor dexterity parameters. J Sports Med Phys Fitness 1987; 27: 478±482 13 Sleivert GG, Rowlands DS. Physical and physiological factors associated with success in the triathlon. Sports Med 1996; 22: 8±18 14 Spring H, Jordan K. Maximal and high-velocity power. A study in Swiss male and female national ski athletes. Schweiz Z Med Traumatol 1994; 2: 27 ± 29 575 Neumayr G et al. Physical Profile of Elite Skiers¼ Int J Sports Med 2003; 24: 571 ±575